Disinfection of irreversible hydrocolloid impressions with sodium hypochlorite steam: Assessment of antimicrobial efficacy

Abstract

Purpose: To evaluate the antimicrobial effectiveness of 2.5% and 5.25% sodium hypochlorite steam to disinfect an irreversible hydrocolloid impressions in Humidifier and Nebulizer Boxes. Methods: The study used a total of 80 quadrant impressions of patients, divided into 4 experimental groups of 20 samples each, with respective controls. The impressions were placed in an atmosphere of sodium hypochlorite with 100% relative humidity for 10 min. After disinfection, each impression was immersed in saline solution that was ultrasonically vibrated. Microbiological analysis of the solution was carried out by counting colonies grown in BHI-agar culture medium after 24 hours in an incubator at 37 oC. The data were analyzed using Wilcoxon’s t test. Results: In all groups, it was found that the mean number of colonies in control groups was higher then in the experimental groups (P<0.0001). There was a significant difference between using the Nebulizer Box and the Humidifier Box when 2.5% sodium hypochlorite was used. At a concentration of 5.25% there was no statistical difference between the mean numbers of colonies for the two methods (P>0.01). Conclusion: Sodium hypochlorite at 5.25% can be used for disinfection in the Humidifier Box and Nebulizer Box methods. However, at a 2.5% concentration it is only effective in the Nebulizer box method.